We would like to investigate the effect of beta, adrenergic blockade on the endogenous and human pancreatic growth hormone-releasing hormone-40 (hpGRF-40) mediated growth hormone (GH) release in children with GH secretory disorders. This will be accomplished by evaluating sequential nocturnal GH values on subjects as a baseline, after atenolol alone, with SQhpGRF-40, and with atenolol plus hpGRF-40.